The sum of the shortest two sides must be longer than the longest side. That is only the case for selection D.
__
If the sum is equal to the longest side, the segment ends will meet, but the "triangle" will look like a line segment. Many authors do not allow such a thing to be called a triangle. Hence, 'b' is not an answer to this question.
(Some authors <em>do</em> allow such a triangle, in which case, there would be two answers here: B and D.)
